Steak in a Sack is a unique and delicious way to cook steak on the barbecue. The steak is marinated in a flavorful mixture of soy sauce, Worcestershire sauce, garlic, and spices, then placed in a foil packet with onions and mushrooms. The packet is sealed and cooked on the barbecue, allowing the steak to cook in its own juices and absorb the flavors of the onions and mushrooms. The result is a tender and flavorful steak that is perfect for a summer barbecue.